Footwear

ABSTRACT

The invention disclosed is directed to skid-resistant footwear having an outer sole provided with grooves and wavy ribs spaced apart by the grooves. Also disclosed is an improved process for making the footwear, including injection molding a bottom onto a footwear upper employing a mold with a bottom plate having wavy elongate uprights.

[ July 23, 1974 United States Patent [1 1 Di Paolo 3,327,334 6/1967\Vilmanns et al. 36/32 R 3,444,632

[ FOOTWEAR 5/1969 Hack et 36/32 R Primary ExaminerPatrick D. LawsonAttorney, Agent, or Firm-John G. Schwartz [22] Filed:

ABSTRACT Related US. Application Data [62] Division of Ser.

No. 216,610, Jan. 10, 1972,

abandoned" The invention disclosed is directed to skid-resistantfootwear having an outer sole provided with grooves and wavy ribs spacedapart by the grooves. Also disclosed is an improved process for makingthe foot- [52] [1.8. 36/32 R [51] Int. A43b 13/04 [58] 36/32 R, 25 R,28, 59 R Field of wear, including injection molding a bottom onto afootwear upper employing a mold with a bottom plate having wavy elongateuprights.

[56] References Cited UNITED STATES PATENTS 2,928,192 3/1960 Green 36/32R 3 Claims, 17 Drawing Figures PATENTED M2319" Fla:

gwmnnma s sueimura FIG. /4

FOOTWEAR This application is a divisional application of Ser. No.216,610; filed Jan. 10, 1972 now abandoned.

The present invention relates to footwear of improved skid resistancehaving an outer sole provided with grooves and wavy ribs spaced apart bythe grooves. The invention also provides improvements in footwear-makingprocesses of the type which include forming and attaching a bottom to anupper by injection molding. The improvements include forming the bottomusing a bottom plate having wavy elongate uprights for providing thegrooves and ribs in the outer sole.

Numerous methods for forming footwear are available to the art.Generally, however, footwear forming methods known heretofore have notbeen entirely satisfactory for reasons such as complexity, inefficiencyand others. Designs for soles of footwear or shoes are taught in U.S.Pat. No. D 1 17,585 to Sperry and in U.S. Pat. No. D 196,355 to Doherty.Soles provided with the Sperry U.S. Pat. No. D 117,585 design includezigzag slits in a smooth surface thereof and are characterized whenat'rest in thatsections formed between the slits are in contact. It is astandard procedure in the shoe making industry to cut or punch slits insole blanks and cut the slit blanks to prepare soles. However, theprocedure has a number of drawbacks in that -sensitivedevices which formthe slits are-easily damaged and cutting soles from blanks typicallyresults in waste of residual blank materials. Attaching the preparedsole to footwear undesirably requires great skill and care which, whennot exercised, often result in formation of low quality footwearreferred to in the art as rejects. In general, soles having the U.S.Pat. No. D 117,585 design have not been entirely satisfactory from notonly the standpoint of skid resistance,- but also from standpoints ofefficiency in forming such soles and in making footwear employingthesoles.

Soles of the Doherty U.S. Pat. No. D l96,355 design include a treadlayer of complex tapering construction which provides less than theamount of ordinarily supportable tread surface desired by many wearers.Footwear provided with soles of such designs are of further limitedutility in that the soles are difficult to clean and when the soles arepressed by the weight of a wearer against non-rigid supports, such assoft carpets and others, objectionable indentations result in thesupports. Moreover, mud and other soils, particularly when wet, tend tocake in the acutely tapering recesses of such soles and after drying,such caking often is undesirably released.

Footwear having a molded bottom attached to an upper is well known inthe art. It is conventional to make such footwear using processes of thetype which include, in general, steps substantially as follows;

a. providing a partial mold assembly having side mold means and a soleplate within the side mold means, said side mold means having an innerperipheral recess corresponding substantially in height to the height ofthe bumper portion of the bottom to be formed, with the side mold meansand the sole plate defining an upwardly open hollow space;

b. inserting a last-and-upper assembly into the hollow space, saidlast-and-upper assembly including a last and a footwear upperdemountably mounted on the last, with the bottom of the upper extendinginwardly under at least the bottom edge of the last, to engage the sidemold means and to provide a molding arrangement having a cavity definedby the lower portion of the lasted-upper assembly, the side mold means,and the sole plate, said molding arrangement having channel meansconnected to said cavity for injection filling the cavity with asolid-forming liquid material;

c. injecting elastomeric solid-forming liquid material through thechannel means to substantially fill the cavity in the moldingarrangement; and

d. permitting the injected liquid material to solidify to form a bottomattached to the upper.

Variations in the process are taught, for example, in U.S. Pat. No.3,345,664 to Ludwig; U.S. Pat. No. 3,372,415 to King; U.S. Pat. No.3,345,763 to Rollman; and in U.S. Pat. No. 3,610,968 to Hobbs et al.

It has now been found by practice of thepresent invention that footwearhaving a skid-resistant outer sole provided with grooves and wavy ribsspaced apart by the grooves is made in simple, economical manner. Suchfootwear may be made in accordance with this invention using minimumhand labor, thus overcoming numerous drawbacks of the prior art.Typically, more than half the labor involved in conventionalfootwearforming methods may thus be eliminated.

Generally stated, the present invention provides improvements inconventional footwear-making processes of the type which is generallyset forth above. The improvements include using in processes of theforegoing type a sole plate having a multiplicity of spaced apartelongate uprights extending transversely of the longitudinal axis of thesole plate in generally parallel wavy relationship one to others, withthickness of the uprights being from about 0.05 to about I millimeterlongitudinally of the sole plate. When made by the improved process ofthis invention, the present footwear may be characterized with betterresistance to skidding without detracting from wear resistance thereofand without sacrificing foot comfort.

Practice of the present invention will become more apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings wherein like numerals refer to similar elementsthroughout the several views.

In the drawings:

FIG. 1 is an elevation view longitudinally of a shoe having a moldedbottom generally illustrating footwear of the present invention;

- FIG. 2 is a plan view of the shoe of FIG. 1 illustrating thegroove-containing outer sole thereof;

FIG. 3 is a longitudinal section of the shoe taken on line 3-3 of FIG.2, with part of the upper removed;

FIG. 4 is a transverse section of the shoe illustrated in FIG. 1 takenon line 4-4 thereof;

FIG. 5 is a transverse section of the shoe of FIG. 1 taken on line 5-5thereof;

FIG. 6 is an enlarged plan view of the part of the bottom within brokenrectangular line 6 of FIG. 2 showing part of the outer sole in greaterdetail;

FIG. 7 is an enlarged longitudinal section taken on line 7-7 of FIG. 2and FIG. 6;

FIG. 8 is an enlarged transverse section taken on line 8-8 of FIG. 2 andFIG. 6;

FIG. 9 is an enlarged transverse section taken on line 9-9 of FIG. 2 andFIG. 6;

FIG. 10 is an elevation section longitudinally of a molding arrangementfor making footwear having a FIG. 14 is an elevation sectiontransversely of the molding arrangement prior to injecting material toform the upper sole;

FIG. 15 is a sectional view similar to FIG. 14, illustrating a shoebottom made using the process; FIG. 16 is an enlarged fragmentarysection of the mold illustrating the shoulder portion of an embodimentlasted upper; and

FIG. 17 illustrates, in a view resembling FIG. 16, embodiment footwearwith the upper more deeply embedded in the upper sole.

Footwear made according to the improved process of this invention isillustrated by. shoe 10 shown in an elevation view in FIGfl, in a bottomplan view in FIG. 2 and in longitudinalelevational section in FIG. 3.The shoe includes upper 11 of suitable flexible material to which isattached bottom part 12 which includes outer sole 14 connected to theupper by bumper portion 16 which is peripheral of the bottom andintegral with inner portion 24 of upper sole 18 (FIG. 3); As shown inFIG 2 generally, and more fully described herein below, the bottomincludes a number of wavy ribs 26 which are spaced apart by amultiplicity of elongate grooves 28 extending transversely of thelongitudinal axis of the shoe in generally parallel wavy relationshipone to others..The grooves must be from about 0.05 to l millimeter inthickness, measure longitudinally of the bottom part. The outer sole mayinclude margins 30 and 31 between opposite ends of the grooves and thebumper portion.

Details in the construction of the shoe are more clearly illustrated bythe sectional view shown in FIGS. 3, 4 and 5, which are taken alonglines 3-3, and 4-4 and 5-5 respectively-(FIGS. l and 2). The bumper oredge portion includes midpart 19 with ridge 20 projecting upwardly fromthe midpart and fitting tightly about upper 11 in outwardly facingportions of the lower shoulder thereof. The bumper includes lowerportion 22 which projects downwardly from the midpart and contains theouter or tread sole 14. The lower shoulder of the upper includes shelf25 extending inwardly of the bumper with lasting string 27 attached tothe edge of the shelf by stitching not shown. The topside of innerportion 24 of the upper sole may be concavely arcuate transversely ofthe shoe, as generally shown in the transverse sectional elevation viewsof FIG. 4 and FIG. 5. Generally, concave upper soles provide greatercomfort to the feet of wearers.

The ribs and grooves provided in the outer sole of footwear madeaccording to this invention are illustrated in greater detail in FIGS.6-9. Generally, the grooves must be from about 0.05 to about! millimeterin thickness, measured longitudinally of the outer sole. It is foundthat grooves which are larger than about 1 millimeter in thickness trapobjects causing discomfort or annoyance to the wearer, while grooveswhich are smaller in thickness generally fail to provide adequate skidresistance to the shoe. The grooves preferably are in the range fromabout 0.2 to about 0.3 millimeter in thickness. The inner portion of theupper sole may be of a foam material. The bumper portion and the treadsurface of the outer or lower sole are preferably of densewear-resistant elastomeric material. The grooves in the outer solepermit flexing of the ribs and reflexing to non-biased position, and aregenerally found to aid in minimizing wear of the sole tread surface.

As a general preference, the grooves are of generally rectangularU-shape in vertical section longitudinally of the shoe. It is found thatgrooves of such shape normally resist clogging with mud or other soilsand at least do not uncontrolably release such soils in the event thatclogging does obtain, thereby increasing the versatility of the shoewith respect to where it may be suitably worn. It is also generallyfound that grooves of thin rectangular shape'provide good balancebetween anticaking and receptivity to water such that good traction isprovided on slippery surfaces, for example, on boats where water oftencollects in slip producing manner. The present shoe is thus eminentlysuitable for use by wearers even on surfaces of boats and other slipperysurfaces.

In a preferred embodiment, the curvature of the grooves bears arelationship to the thickness thereof such that the ribs provided in thesole are solid in transverse vertical section taken, as at line 8-8 (andshown in FIG. 8) forwardly of the foremost parts of the rear face of arib and rearwardly of the rearmost parts of the forward face of the samerib.- As used herein, the words forward, forwardly and foremost refer tothe forward or toe end of the sole- (or the direction thereof), thelocation of which is indicated in FIG. 6 by directional arrow 34; andthe rearward, rearwardly and rearmost refer to the opposite or heel endof the sole (or the direction thereof), the location of whichisindicated by directional arrow 34.

The sides of the various grooves which appear as wavy lines transverselyof the sole in the plan view of FIG. 6 include a plurality of spacedapart arcuate toewardly convex portions and a plurality of spaced apartarcuate toewardly concave portions, generally as illustrated, with theconvex portions connected one to others in repeated manner by theconcave portions and with the concave portions connected one to othersin repeated manner by the convex portions. It is unexpectedly found thatskid resistance is further improved by providing grooves having sidescharacterized in that the average radius r of the arcuate side portionswhich face in a first direction is relatively small with respect to theaverage radius R of the arcuate portions facing in the oppositedirection as shown in FIG. 6.

While the grooves may be of almost any depth, groove depth of about 2 toabout 5 millimeters is found suitable. Flexibility of the ribs isdependent on the material of which the lower sole is formed. In general,however, suitable flexibility is provided by ribs having longitudinalthickness corresponding to from about 0.8 to about 2 times the depth ofthe grooves. A sole which is generally preferred includes, incombination, ribs having longitudinal thickness from about 2 to about 3millimeters and grooves having longitudinal thickness of about 0.1 toabout 0.3 millimeter and depth of about 2 to about 3 millimeters. Ingeneral, ribs corresponding in thickness to more than about 5 times thedepth of the grooves are insufficiently flexible to provide adequateskid resistance.

As used herein, the term elastomer means any and all plastics orplastic-like materials embodying characteristics of resiliency andcapability of being rendered plastic for a sufficient length of time tobe injected into a mold to form the bottom part of a shoe and to be thencaused to set, cure, harden, solidify or otherwise become relativelydimensionally stable. Suitable solidforming liquid materials which maybe used to form the bottom of the shoe are exemplified by, but notlimited to, polyvinyl chloride mixtures, rubber, polyurethane mixturesand the like.

Referring to FIGS. -15, the present process for making footwear,illustrated by shoe 10, includes providing a mold assembly having sidemold means, illustrated by split ring side molds 36, and sole plate 38.In accordance with this invention, the'sole plate has a multiplicity ofwavy elongate uprights 40 extending transversely of the longitudinalaxis of the plate in generally parallel relationship one to others forproviding grooves 28 in shoe 10.The thickness of the uprights generallymust be from about0.05 to about 1 millimeter longitudinally of the soleplate. It is found that uprights which are more than on 1 millimeterin-thickness form unsuitably thick grooves in outer soles, whileuprights which are less than 0.05 millimeter in thickness are ofinadequate damage resistance for economical use thereof. For greaterprotection against these and other undesirable results, the uprightspreferably are of I thickness in the range of from about 0.2 to about0.3

millimeter. Split ring side mold 36 includes inner peripheral recess 42corresponding substantially in height to the height of the bumperportion of the bottom to be formed, with the side mold and the soleplate defining an upwardly open hollow space. The side mold includes lip43 above recess 42 for engagement with a lasted upper inserted into thehollow space. A lasted upper assembly including upper 11 lasted aboutlast 54 is inserted into the mold space to form a molding arrangementwherein the lasted upper is in engagement with mold lip 43 and havingcavity 45 (FIG. 10) defined by the lower portion of the lasted upperassembly, the side mold, and the sole plate. The molding arrangement isprovided with means for injection filling cavity 45 as illustrated bypassage 44 which connects recess 42 to the outer edge of the side moldand may have a tapered end for receiving an outlet nozzle of aninjection extruder. Sole plate 38 may be provided with means forinjecting elastomeric material as illustrated by passage 46 having afirst port 48 in plate surface 49 and a second port 50 for flowcommunication with passage 52 provided in the side mold (FIGS. 12 and13).

The lasted upper assembly may be any suitable arrangement of an upper ona last, examples of which include Mackay lasted uppers, vertical weltand string lasted uppers, and lasted uppers with sewn-in upper soles forcontacting the foot of a wearer.

Elastomeric solid-forming liquid material is injected as through passage44 to substantially fill the cavity 45 (FIGS. 10 and 14) while the soleplate is in a first position characterized in that bottom edge 53 of therecess in the side mold is below the shoulder of the sole plate as shownin FIGS. 10, 11 and 14. The sole plate is maintained in the firstposition until the injected material solidifies or hardens substantiallythroughout to form upper sole 18 attached to the upper and having bumperportion 16 peripherally of inner portion 24 of the upper sole as shownin FIG. 11. It is found that sole plates formed of aluminum or alloysthereof or almost any material of thermal conductivity on the order ofthat of aluminum reduce the time for solidification to take place.Uprights 40 are found to aid in minimizing solidification time. Theplate may be provided with additional means for cooling such as holes(not shown) with cooling water circulated therethrough.

After upper sole 18 sets or solidifies to form a dimensionally stablestructure, the sole plate is lowered to a second position characterizedin that the bottom edge of the recess is slightly above the shoulder ofthe plate, thus providing cavity 47 within downwardly projecting portion22 of the bumper 16 as shown in FIG. 12. Cavity 47 may then be filled byinjecting solid-forming liquid material through passage 52, port 50,passage 46 and port 48 in sufficient amount to at least substantiallyfill the cavity. The plate is maintained in the second position for asuitable time to permit setting or solidification of the injectedmaterial, resulting in formation and bonding of I groovecontaining outersole 14 to upper sole 18 as shown in FIGS. 13 and 15. The mold isthereafter opened as by retracting a half-ring of the side mold topermit removal of the molded bottom shoe which may be demounted from thelast in any suitable manner.

Residual injection molding material may be with? drawn from the variouspassages in any suitable manner as by means of sprue extractor apparatusdisclosed in US. Pat. No. 3,588,958 to Metzger.

The solemay have upright-free margins between the opposite ends of theuprights and the peripheral edge of the sole plate, the sole platemargins corresponding to margins 30 and 31 of the outer sole as shown inFIG. 2. It is found that sole plates having margins provide longer andmore efficient service with less accidental damage to the uprights. I

In footwear made by the above-described two-step injection embodiment ofthe present improved process and illustrated by shoe 10, wavy elongateprojections 56 of the outer sole 14 are tightly received incorresponding grooves 58 in the upper sole, thereby providing addedstrength to the bond. The two-step injection process has the addedadvantage that different plastic compositions may be used for the uppersole and for the outer sole. The different compositions may also differin color, thereby providing greater versatility.

Optionally, outer sole l4 and upper sole 18 may be formed of one piececonstruction in a one-step injection operation in which the sole plateis initially placed in the second position, i.e., omitting the firstplate position and injecting solid-forming liquid material into theresulting cavity.

While the bottom of the outer sole may have any suitable shape, it isfound that generally better skid resistance and increased bottomdurability are provided by a preferred embodiment of the present processusing a sole plate with the sole plate surface 49 arcuately taperinglongitudinally upwardly from generally about the middle of the soleplate or slightly forward thereof to within a one inch region near thetoe end in a manner corresponding generally to longitudinally arcuateforward portion 15 of the outer sole as illustrated in FIG. 1. Theforward portion of the outer sole may be formed of transversely arcuateupwardly concave shape as 7 shown in FIG. 4 by molding with a sole platethe forward portion of which is transversely arcuate as shown in FIG.15.

Sole plates for use herein may be formed using any suitable formingmethod. For example, the sole plate may be made from an appropriatepiece of metal stock, preferably aluminum or aluminum alloy stock, usingconventional milling techniques.

The shape of the uprights provided on the sole plate should besubstantially the same as the shape of the grooves to be provided in theouter sole being formed. Thus, as a general preference, the uprights aregenerally of rectangular U-shape in vertical section longitudinally ofthe sole plate. The tops of the uprights may suitably be above the soleplate surface across which the uprights extend by from about 2 to about5 millimeters. Spacing between the uprights may be from about 0.8 toabout 2 times the height of the uprights. A generally preferred shoe ismade using a sole plate with uprights spaced apart at a distance fromabout 2 to about 3 millimeters, the uprights being from about 0.1 toabout 0.3 millimeter in thickness longitudinally of the sole plate andfrom about 2 to about 3 millimeters in height as measured between thetops of the uprights and the sole plate surface across which theuprights extend. The uprights may have sides characterized in that theaverage radius of arcuate side portions facing in a first direction issmall relative to the average radius of oppositely facing side portions,corresponding to the grooves illustrated in FIG. 6. Where sole platemargins corresponding to outer sole margins 30 and 31 are included, theypreferably are at least about one millimeter in width transversely ofthe sole plate.

The enlarged fragmentary view of FIG. 16 (corresponding to a portion ofFIG. 14) and the enlarged fragmentary view shown in FIG. 17(corresponding to a portion of FIG. show an arrangement of the upper onthe last in another embodiment of this process. It is seen that thelower margin or shelf 25 of the upper may be drawn by string 27 to aposition tapering inwardly and slightly downwardly away from last 54.Upon injection molding in the foregoing manner, this embodiment resultsin further embedding the shelf and string in the molded bottom and thusprovides a smoother foot contacting surface to the added comfort of thewearer.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that various modifications may be madetherein, including in the improvements provided by the present inventionand in the basic heretofore known process, without departing from thespirit or scope of the present inventlon.

What is claimed is:

l. Footwear comprising, in combination, a flexible upper and a bottompart having an outer sole connected to the upper by a bumper portionperipheral of the footwear and integral with an upper sole, the bottomof said outer sole having a number of wavy ribs spaced apart by amultiplicity of elongate grooves extending transversly of thelongitudinal axis of the footwear in generally parallel wavyrelationship one to the others, with thickness of the grooves being fromabout 0.05 to about 1 millimeter longitudinally of the footwear, thegrooves being of generally U-s hape in vertical section longitudinallyof the footwear, said bottom part having been formed and attached to theupper by solidification of elastomeric solid-forming liquid material ina mold.

2. The footwear of claim 1 wherein the wavy ribs have first arcuate sideportions facing in a first direction and are connected by oppositelyfacing arcuate portions, the average radius of the first arcuateportions being relatively smaller than the average radius of theoppositely facing arcuate portions.

3. The footwear of claim 1 wherein the outer sole and the bumper havingthe upper sole integral therewith are all of one-piece construction.

1. Footwear comprising, in combination, a flexible upper and a bottompart having an outer sole connected to the upper by a bumper portionperipheral of the footwear and integral with an upper sole, the bottomof said outer sole having a number of wavy ribs spaced apart by amultiplicity of elongate grooves extending transversly of thelongitudinal axis of the footwear in generally parallel wavyrelationship one to the others, with thickness of the grooves being fromabout 0.05 to about 1 millimeter longitudinally of the footwear, thegrooves being of generally Ushape in vertical section longitudinally ofthe footwear, said bottom part having been formed and attached to theupper by solidification of elastomeric solid-forming liquid material ina mold.
 2. The footwear of claim 1 wherein the wavy ribs have firstarcuate side portions facing in a first direction and are connected byoppositely facing arcuate portions, the average radius of the firstarcuate portions being relatively smaller than the average radius of theoppositely facing arcuate portions.
 3. The footwear of claim 1 whereinthe outer sole and the bumper having the upper sole integral therewithare all of one-piece construction.